NEW YORK (AP) — Tiny metal buttons in delicious-sounding colors like poupon, hubba bubba and piglet have served as The Metropolitan Museum of Art’s admission ticket for 42 years. But starting Monday, the 1-inch disks will be replaced by a paper ticket with detachable sticker.

It’s all about the money — the buttons have become too expensive to produce.

“The cost has been increasing exponentially over the years,” said Harold Holzer, the museum’s spokesman. “It’s gone up tens of thousands of dollars in the last five years.”

When the museum first started using the buttons, it had about 1 million visitors annually. Today it has 6 million.

“It seems impractical to tie ourselves to an archaic, quaint — even if it’s well liked — system,” he added.

The buttons are making their exit on the same day that the Met is switching to a seven-day-a-week schedule. The museum — which has a recommended admission of $25 for adults, meaning visitors may pay what they wish — had been closed Mondays.

“The message is not changing, the medium is changing,” Holzer said.

In 1997, a student at Parson School of Design created a dress with the buttons for a project using recycled objects. It features three of the 16 colors the buttons came in. The piece was donated to the museum and is in storage.

Like the buttons, the paper tickets will eventually come in an assortment of colors. The first will be el mar blue. They also will contain a date (something the buttons lacked) and be emblazoned with the same “M” design used on the buttons, adapted from a 16th-century illustration based on a Leonardo Da Vinci drawing.

“With just a flip of a computer switch,” the paper tickets will allow the museum to issue timed-entry tickets for such special shows as the wildly popular Alexander McQueen costume exhibition in 2011, Holzer said.

“It gives us a great deal of agility,” he said. “Agility beats nostalgia every time.”

Asked if the button might become an art object worthy of museum display, Holzer quipped: “It’s been displayed about a hundred million times if you count all the visitors who’ve worn it. It’s maybe time for a rest.”